French patent No. 1 533 266 discloses a metal-clad bay comprising, for each phase, a rotary interrupter apparatus, with rotation of the apparatus about an axis lying in a virtual plane of symmetry of the bay providing section isolation therefore.
It has not been possible to construct that apparatus industrially because of the large volume and weight of the sealed type interrupter apparatuses containing a non-flammable fluid that are proposed, in particular sulfide hexafluoride (SF.sub.6) circuit-breakers. Another handicap results from the length of the stroke of the SF.sub.6 circuit-breakers which penalizes the above-mentioned type of apparatus because of the excessive length required.
German petty-patent No. 1 870 065 also discloses a circuit-breaker whose poles are disposed on a horizontal bar capable of pivoting about its axis and of providing the section-isolating function of the circuit-breaker. When the circuit-breaker is in its disconnecting position, its poles are inclined and as a result its isolation distance is reduced, thereby requiring the apparatus to be over-dimensioned in order to obtain dielectric strength. Another drawback of that device is that when it is in its isolating position, its poles are at a potential that is not determined (floating potential).
Another drawback of the circuit-breaker described in the above-mentioned document is the need to use an insulating plate to isolate the front face of the apparatus when the circuit-breaker is extracted.
Another drawback is that in the event of excess voltage between a set of busbars and cables, the gap between said elements may be bridged by an arc.
Another drawback is that the poles of the circuit-breaker are necessarily controlled by rotation and cannot be controlled by a push-pull action.
Another drawback is that the poles must be provided with connectors for making connection with the busbars or with the cable heads, and this excludes any direct engagement.
A first object of the invention is to provide a multi-pole self-disconnecting circuit-breaker of low weight and small size in all dimensions, thus making it easily received in a bay and easily driven without requiring high driving energy.
Another object of the invention is to provide a self-disconnecting circuit-breaker at low cost.
Another object of the invention is to provide a self-disconnecting circuit-breaker in which the items relating to the various poles, in general three poles for a three-phase apparatus, can be placed in the same extractible drawer in a cabinet of a bay, with easy front access to the outgoing cables and to the set of busbars in a station constituted by juxtaposing a plurality of bays.
Another object of the invention is to provide a self-disconnecting circuit-breaker that is easily inspected, and enabling pole equipment to be interchanged or enabling an entire pole to be replaced.
Another object of the invention is to provide a self-disconnecting circuit-breaker that avoids the above-mentioned drawbacks of the prior art.
Another object of the invention is to provide a medium tension bay provided with the self-disconnecting circuit-breaker of the invention, said medium-tension bay enabling current to be interrupted, section isolation to be obtained upstream and downstream, and current to be detected to provide protection against short circuits, said bay including all of the items required for supporting the set of busbars, for anchoring the cables, for visible earthing with a visible indication that voltage is present, for separating the cable compartments and the sets of busbars, for driving the circuit breaking and disconnecting functions, and for extraction purposes when, exceptionally, it is necessary to inspect the self-disconnecting circuit-breaker.
An object of the invention is to provide a bay of the above-specified type that occupies considerably less ground area than analogous bays of the prior art.
Another object of the invention is to provide a bay of the above-specified type in which the risks of faults between phases are very low.
Another object of the invention is to provide a medium tension station that is cheap to construct, in which the risks of a fault appearing between phases are extremely low and in which the risks of a ground fault propagating and progressing are very low.